Magnet lifting yoke



Dee. 30, 1969 MAGNET LIFTING YOKE Filed Oct. 18. 1967 INVINTOR senr Ndnlmu e.: Lewrseu B.N..EJLERTSEN I 3,486,784-

United States Patent O 3,486,784 MAGNET LIFTING YOKE Bent N. Ejlertsen, Herlev, Denmark, assignor to H. Nielsen & Son Masknfabrik Aktieselskab, Copenhagen, Denmark Filed Oct. 18, 1967, Ser. No. 676,252 Claims priority, applicsation Denmark, Nov. 2, 1966,

04/ 66 Int. Cl. B66c 1 04; E21b 31 06 U.S. Cl. 294-655 9 Claims ABSTRACT OF THE DISCLOSURE A yoke for lifting iron bars consisting of a box-shaped girder beneath which a number of long, narrow electromagnets are rotatably suspended by means of a shaft in the girder. Each magnet carries at its ends end pins suspended by means of slings or ropes. These slings are connected with spring means in the girder and with said shaft so that slings can be moved for vertical displacement and for turning the magnet. Preferably each sling is passed around its separate pulley in its separate spring means and then down and attached to the shaft.

BACKGROUND OP THE INVENTION Field of the invention Description of the` prior art From the Danish patent specification No. 93,311 are known magnet lifting yokes of this kind in which the electromagnets are coupled together by means of shaft sections mounted between the magnets and connected to these by means of cardan joints. The shaft thus composed is connected at one end with a control bar provided with a handle. When the said handle is turned, the magnets can be turned about the axes of their end pins, the axes being substantially parallel with the longitudinal axis of the magnet yoke. When the magnet yoke has lifted an iron bar or girder, it has been found dicult to turn the said bar or girder by turning the magnets because this operation requires the transmission of a torque from the handle to the magnets, and such a torque is diicult to transmit by means of the cardan joints. Owing to the location of the handle at one end of the composed shaft, the cardan joints close to the said end are subject to a very heavy torque, resulting in excessive wear with consequent clearance, which requires frequent replacement of the said parts.

SUMMARY OF THE INVENTION The object of the invention is to provide a magnet lifting yoke whose shaft for turning the magnets may be securely m-ounted in the magnet yoke, and to provide a shaft which may be manufactured as a long undivided length.

This is accomplished according to the invention by forming the magnet yoke in such manner that the individual magnet with its end pins is suspended by means of slings or ropes connected with the spring means and 3,486,784 Patented Dec. 30, 1969 the shaft in such manner that they can ibe moved both for vertical displacement and for turning the magnet. Because the turning and carrying of each magnet are performed by one and the same element, that is, the slings or ropes, the magnet suspension obtained is very simple and robust.

According to the invention the yoke may be adapted in such manner that the shaft for turning the magnets rests in fixed bearings provided in the girder, each of the slings or ropes being passed up around its separate pulley in its separate spring means and then down and attached to the shaft. The latter does thereby not take part in the resilient movement, but may be supported in fixed bearings provided in the yoke.

According to the invention the slings or ropes may be wound at least once around the shaft and attached to same. As a result, the magnets can be turned through a desired angle by turning the shaft, and if, more particularly, the shaft is made with a diameter somewhat smaller than the diameter of the end pins of the magnets, an advantageous ratio of gearing between shaft and end pins will be obtained. The magnets can therefore be turned exactly into such position that they are caused to rest with their entire supporting surface in abutment against the iiange of the steel joist involved when the said ange forms an angle to a horizontal plane.

The shaft may further according to the invention carry twin arms to which the ends of the slings are fastened. Windings of the slings around the twin arms are thereby avoided.

The shaft may in a suitable embodiment according to the invention carry rope pulleys to which the ends of the slings are attached. The result obtained in that case is proportionality between the turning angles of the shaft and the magnets.

Further according to the invention the shaft may be mechanically connected with a driving motor, for example a gear motor which is m-ounted on or in the magnet lifting yoke at its central part. This will produce low torques at both ends of the shaft compared with the case in which the torque of the driving motor is transmitted to the driving shaft at one end of the magnet yoke as in the known magnet yokes.

BRIEF DESCRIPTION OF THE DRAWING The invention will now be further described with reference to the accompanying drawing, in which- FIGURE 1 shows fractions of a magnet lifting yoke with supension means and magnets and a rolled steel joist carried by these and viewed from the side,

FIGURE 2 shows on a larger scale a section taken upon the line II-II of FIGURE 1, and

FIGURE 3 in corresponding manner shows a modication of a magnet lifting yoke in which the shaft carries twin arms.

FIGURE 1 shows a magnet lifting yoke which is suspended in known manner by suspension means 1 from the crab of a hoisting apparatus. The magnet yoke is designed as a box-shaped girder 2 consisting of a main beam 3 and a foot beam 4. The said beams are interconnected by means of two lattice sections 5. Beneath and along the girder 2 are mounted a number of electromagnets 6 lifting a steel joist 7 as shown in FIGURE l. The magnets 6 carry at each of their ends end pins 8 in which the magnets are rotatably suspended by means of slings or ropes 9. At their upper ends the said slings are connected with spring means 10 (FIGURE 2) mounted in the main beam 3 of the girder 2 so that the springs 11 of the spring means are protected from damage. This resilient suspension in the direction of lifting will ensure an approximately equal distribution of the load lifted by the magnets. As will be seen, the slings 9 serve both as suspension elements and as rotational elements for the magnets 6.

At the central part of the magnet yoke is provided a driving motor 12, for example a gear motor, which is connected by means of a chain 13 with a shaft 14 for turning the magnets 6. The shaft 14 is carried by xed bearings (not shown) provided in the girder beneath the spring means 10, and it extends ,along the girder in the entire length of same.

As shown in FIGURE 2, the sling 9 is passed from the electromagnet 6 through the foot beam 4 up around a pulley 15 which rests in a fork 16 mounted in the spring means 10. From the pulley 15 the sling 9 is passed down and attached to the shaft 14. The sling 9 may be wound at least once around the shaft 14. The said shaft may carry a rope pulley 17 indicated by dots on FIGURE 2, the ends of the sling 9 being attached to the said pulley.

FIGURE 3 shows an embodiment in which the shaft 14 carries twin arms 18 to which the ends of the sling 9 are attached.

I claim:

1. Apparatus for lifting elongated members of magnetizable material such as rolled steel joists, the apparatus comprising in combination; a girder, a plurality of magnets disposed below the girder in end to end relationship, and means suspending said magnets below the girder for rotation relative to the girder about the axes of the magnets, said means including pulleys, resilient means suspending the pulleys from the girder, and slings received about the pulleys and portions on said magnets to rotate said magnets in response to rotation of the pulleys.

2. The apparatus dened in claim 1 wherein said means further includes a shaft mounted on said girder in generally parallel relationship therewith and for rotation relative to the girder, and wherein said -slings are connected around said shaft to be moved in response to rotation of said shaft.

3. The apparatus defined in claim 2 further including a motor mounted on said girder and means operatively connecting said motor to said shaft to drive the shaft in rotation.

4. The apparatus defined in claim 2 wherein said magnets have pins projecting from the opposite ends thereof and wherein said slings are received about. said pins.

5. The apparatus defined in claim 2 wherein said resilient means includes yoke members with said pulleys rotatably mounted therein; .and means including springs suspending said yoke members from the girder.

6. The apparatus dened in claim 2 wherein said girder includes an upper main beam, a lower foot beam and means interconnecting said beams to form a generally rectangular girder, and wherein said pulleys are suspended from said main beam and said magnets are located below said foot beam with said slings passing through said foot beam.

7. The apparatusdened in claim 2 wherein said slings are wound at least once around said shaft.

8. The apparatus defined in claim 2 wherein said shaft carries twin arms to which the ends of the slings are attached.

9. The apparatus defined in claim 2 wherein said shaft carries pulleys to which the ends of the slings are attached.

References Cited FOREIGN PATENTS 1,141,061 12/1962 Germany.

ANDRES H. NIELSEN, Primary Examiner 

